Increasing demand for the use of gold in various applications including micro-electronic circuits and electrical contact devices has renewed interest in gold plating technology. Both electroless and electroplating gold are of importance. In particular, the procedure for making gold compounds useful in gold plating technology is of major concern. Gold cyanide is useful in gold plating technology in a variety of ways, including replenishment of plating baths. This compound is particularly advantageous in this application because its addition to plating baths does not alter salt concentration. This permits replenishment of a gold plating bath without excessive increase in pH and the concentration of alkali-metal ion and cyanide ion.
Generally, AuCN is prepared by the acidification of KAu(CN).sub.2. However, this process generates highly toxic HCN gas which requires special handling and treatment before disposal. Similarly, other methods available for the manufacture of AuCN liberate toxic gases. For example, the precipitation of a solution of AuCl.sub.3 with KCN liberates the highly poisonous cyanogen gas (CN).sub.2. Consequently, it is highly desirable, for commercial and safety reasons, to be able to prepare AuCN without evolving toxic gases. It is also desirable to minimize loss of gold. Thus, high yield (close to 100%) is desirable and the AuCN formed should be relatively pure. In addition, process simplicity and low cost are desirable.